Method for building liquefied-gas-carrier

ABSTRACT

A method for building a liquefied-gas-carrier wherein a lower hull subassembly having a tank mounted thereupon is inserted into an upper hull subassembly assembled at a predetermined place on a shipway and are joined to each other to thereby form a unit tank section, and a plurality of unit tank sections assembled in the same manner are joined one by one to build the hull of the ship.

i a Unite States atent 1 1 1111 3,922,986

Minamizaki et al. Dec. 2, 1975 METHOD FOR BUILDING 3,828,708 8/1974 Gerwick ct ul 114/74 R LIQUEFIED'GAS'CARRIER FOREIGN PATENTS OR APPLICATIONS [751 Inventors- A y i i z Yagi 1,507,407 11/1967 France 114/77 R 0t 0 o 0 ama; ensu e $g gg jg lz Primary ExaminerGeorge E. A. Halvosa p Assistant ExaminerGregory W OConnor [73] Assignee'. lshikawajima-Harima Juk0gy0 Attorney, Agent, or FirmScrivener Parker Scrivener Kabushiki Kaisha, Tokyo, Japan & Clarke [22] Filed: July 2, 1974 21 Appl. No.: 485,082 [57] ABSTRACT A method for building a liquefied-gas-carrier wherein a lower hull subassembly having a tank mounted 2555 thereupon is inserted into an upper hull subassembly [58] Fie'ld A 77 77 A 74 R assembled at a predetermined place on a shipway and 226/9 are joined to each other to thereby form a unit tank section, and a plurality of unit tank sections assembled References Cited in the same manner are joined one by one to build the hull of the shi UNITED STATES PATENTS p 3,765,359 10/1973 Takezawa [14/65 R 3 Claims, Drawing Flgul'es Sheet 2 of 2 US. Patent Dec. 2, 1975 METHOD FOR BUILDING LIQUEFIED-GAS-CARRIER DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for building liquefied-gas-carriers.

To erect or assemble unit tank in a ship hull (the unit tank being made of stainless steel, aluminum alloy, or nickel alloy), the prior art employs A. a method for lowering the tanks through an-opening in the upper deck into the hull when the hull has been almost completed; or

B. a method in which the tanks are erected upon the double bottom and thereafter the side plating blocks, transverse bulkheads, upper deck blocks and so on are erected.

Both of the above prior art methods present no problem when a relatively small vessel is built,'but when they are employed in building a large liquefied-gascargo ship in excess of 100,000 m the following problems arise:

1. Large cranes and installation apparatus must be used, thus resulting in the increase in cost.

2. Works for installing heat insulating layers or structures around the tanks cannot be isolated from the hull construction which requires gas cutting, welding and so on so that the possibility of accidents due to fire present serious problems.

3. There must be provided a sufficient space between the hull and the tanks inside the hull in order to install the heat insulation layers or structures around the tanks and to assemble the hull so that the volume of the tank will become limited. In other words, the volumetric efficiency of the tank, i.e., the ratio of the volume of the tank to the dimensions of ship, is less efficient.

One of the objects of the present invention is therefore to overcome the above problems. Another object of the present invention is to provide a method which makes it possible to build a large liquefied-gas-carrier within a short period and without causing any accident at a less installation cost. A further object of the present invention is'to provide a method which makes it easier to insert a lower hull subassembly into a mating upper hull subassembly in assembling a unit tank section.

The present invention will become more apparent from the following description of one preferred embodiment thereof taken in conjunction with the accom-' panying drawing in which:

FIG. 1 is a view illustrating the sequence of steps of .shipbuilding in accordance with the present invention;

FIG. 2 is a perspective view illustrating one method for inserting a lower hull subassembly with a tank mounted thereupon into an upper hull subassembly; and

FIG. 3 is a view similar to FIG. 2 illustrating another method for inserting a lower hull subassembly into an upper hull assembly.

FIG. 2 shows, on enlarged scale, a tank section indicated by e in FIG. 1, and the shipbuilding method in accordance with the present invention will be described in detail with reference to FIG. 2.

A lower hull subassembly I is built upon supports 11 by laying a double bottom block 1, erecting a transverse bulkhead 2 and then installing a heat insulating layer 3. Thereafter, a tank 4 is built upon the double 5 5 lined with a heat insulating'layer 8 and the upper deck block 7 whose lower side is also lined with a heat insulating layer 9 are erected, aligned and welded together and connected to the side plating blocks 5 and the upper deck 7' of the next tank section f. During the erection of the upper hull subassembly II, the upper deck block 7 is supported by a plurality of temporary supporting columns (not shown). The other side plating block 6, which is supported on a side plating block carriage 10, is displaced-transversely by a distance 0: so that the lower hull subassembly I with the tank 4 mounted thereupon may be easily inserted into the upper hull subassembly II. However when the arrangement or design of the upper and lower hull subassemblies I and II are such that the lower hull subassembly I may be inserted into the upper hull subassembly II without the other side plating block 6 displaced transversely, the other side plating block 6 may be directly joined to the upper deck block 7 and to the upper deck block 7' and the side plating block 6' of the next tank section f.

Next the lower hull subassembly I supported by the supports 11 is inserted .into the upper hull subassembly II in the direction indicated by the arrow X, and thereafter the carriage 10 is moved transversely in the direction indicated by the arrow Y by a distance a so that the other side plating block 6 may be located at the correct position. Next the other side plating block 6 is welded to the upper deck block 7 and the side plating block 6' of the next tank section f. Thereafter, the lower hull subassembly I is welded to the upper hull subassembly II (When the other side plating block 6 has been already joined to the upper deck block 7, the lower hull subassembly I is immediately welded to the upper hull subassembly II after the former has been inserted into the latter). Afterthe upper and lower hull subassemblies II and I have been welded together, the heat insulating layers 3, 8, and 9 are joined by a suitable manner. Thus the assembly of the tank section e is completed.

In like manner, the tank sections f, e, d and c on the stern side are assembled in the order named as shown in FIG. 1 while the tank sections a and b are assembled on the bow side. More particularly, after the tank section f is assembled, the assembly of the tank sections e and a are started simultaneously as shown in FIG. 1(C), and then the assembly of the tanks sections d and b are started as shown in FIG. 1(D). Thereafter the tank section 0 is assembled as shown in FIG. 1(E), and finally the bow and stem sections are joined together as shown in FIG. 1(G). Thus, a liquefied-gas-carrier is built.

Next referring to FIG. 3, another method for assemblying the lower hull assembly I with the upper hull assembly II will be described. One side (close to the stern in case of the tank section on the stern side or close to the bow in case of the tank section on the bow side) of the side plating block 6 is joined with hinges 12 to the side plating block 6 of the tank section which has. been already assembled. The side plating block 6 is supported by the side plating supporting carriage l0 and is joined to the upper deck block 7 with means 13 which are adapted to pull the side plating block 6 toward the upper deck 7 and to support the side plating block 6. Therefore the side plating block 6 may swing outwardly about the hinges 12 with an angle a until the lower hull subassembly l is inserted into the upper hull subassembly ll. After the insertion of the lower hull subassembly I into the upper hull subassembly II, the carriage is moved in the direction indicated by the arrow Y while the means 13 pull the side plating block 6 toward the upper deck block 7. Therefore the side plating block 6 is aligned with other structures, and welded to them.

It is to be understood that the present invention is not limited to the above two embodiments and that any suitable means and methods may be employed in order to displace one of the side plating blocks of the upper hull subassembly from its normal position so that the lower hull subassembly may be inserted into the upper hull subassembly.

The advantages of the present invention may be summarized as follows:

i. The time required for building a liquefied-gas-carrier may be considerably reduced because the tanks and the hull subassemblies are built separately and also because the bow and stern section are assembled separately.

ii. Since the tanks and the hull subassemblies are built separately, the unit size of the side plating and upper deck blocks will be reduced with the result of the reduction in cost of the hoisting machines such as cranes.

iii. According to the prior art methods, the works for installing heat insulating layers are generally done in a limited narrow space between the tank and the hull, but according to the present invention, the space for insulating works can be neglected so that the volumetric efficiency of the tank will be considerably improved.

iv. Because of the reason described in (iii), the possibility of fire accidents of the heat insulating layers or structures will be minimized so that the safety in shipbuilding works can be assured.

v. According to the prior art methods, a very large roof must be built in order to protect the heat insulating layers or structures against rain, but according to the present invention, the heat insulating layers or structure installation is completed as one tank section is 4 completed so that the area of a roof will be minimized with the result of the reduction in installation cost.

vi. One of the side plating blocks of an upper hull subassembly may be displaced from its normal position so that a lower hull substructure will be very easily inserted into the upper hull subassembly.

vii. Since the carriage and means for supporting the side plating block are used, the displacement of the side plating block is easy and may be done very fast.

viii. When the side plating block is so arranged as to swing about the hinges joined at one side thereof, the alignment of the side plating block will be very easily attained after the lower hull subassembly is inserted into the upper hull subassembly.

What is claimed is:

1. A method for building a liquefied-gas-carrier wherein assemblying an upper hull subassembly including a side plating block at a predetermined place on a shipway, inserting a lower hull subassembly having a tank mounted thereupon into said upper hull subassembly, joining said lower hull subassembly to said upper hull subassembly, thereby assemblying a unit tank section, and joining a plurality of unit tank sections to thereby build a ship, wherein said side plating block of said upper hull subassembly is temporarily held in position displaced outwardly from its normal position and is returned to its normal position after said lower hull subassembly is inserted into said upper hull subassembly.

2. A method as defined in claim 1 wherein said side plating block of said upper hull subassembly is temporarily held by means, which supports said one side plating block for movement, at a position displaced outwardly from its normal position, and returned to its normal position by said supporting means after said lower hull subassembly is inserted into said upper hull subassembly.

3. A method as defined in claim 1 wherein said side plating block of said upper hull subassembly has its one side hinged so that said one side plating block may swing outwardly from its normal position and may be returned to its normal position after said lower hull subassembly is inserted into said upper hull subassembly. 

1. A method for building a liquefied-gas-carrier wherein assemblying an upper hull subassembly including a side plating block at a predetermined place on a shipway, inserting a lower hull subassembly having a tank mounted thereupon into said upper hull subassembly, joining said lower hull subassembly to said upper hull subassembly, thereby assemblying a unit tank section, and joining a plurality of unit tank sections to thereby build a ship, wherein said side plating block of said upper hull subassembly is temporarily held in position displaced outwardly from its normal position and is returned to its normal position after said lower hull subassembly is inserted into said upper hull subassembly.
 2. A method as defined in claim 1 wherein said side plating block of said upper hull subassembly is temporarily held by means, which supports said one side plating block for movement, at a position displaced outwardly from its normal position, and returned to its normal position by said supporting means after said lower hull subassembly is inserted into said upper hull subassembly.
 3. A method as defined in claim 1 wherein said side plating block of said uppeR hull subassembly has its one side hinged so that said one side plating block may swing outwardly from its normal position and may be returned to its normal position after said lower hull subassembly is inserted into said upper hull subassembly. 